1. Field of the Invention
The present invention relates to a light source unit which includes a fluorescent wheel and a projector which includes the light source unit.
2. Description of the Related Art
In these days, data projectors are used on many cases as image projection apparatuses which project screens and video images of personal computers and further images based on image data stored in memory cards on to a screen. These projectors are such that light emitted from a light source is concentrated to a micromirror device called DMD (Digital Micromirror Device) or a liquid crystal plate for display a color image onto the screen.
In projectors of the type described above, conventionally, projectors using a high-intensity discharge lamp as a light source have been the mainstream of projectors. In recent years, however, there have been made many developments and proposals on light source unit which use, as a light emitting device of a light source unit, a semiconductor light emitting device such as a light emitting diode (LED), a laser diode (LD), or a device utilizing organic EL technology.
For example, Japanese Unexamined Patent Publication No. 2004-220015 (JP-A-2004-220015) proposes a light source unit including the light emitting devices in which the light emitting devices are disposed in a matrix-like configuration in order to increase the quantity of light. However, in the invention described in the patent document, the number of bright points of the light emitting devices is increased, and this causes a problem that the light utilization efficiency of light emitted from the respective light emitting diodes is reduced due to the Etendue value of the light source which is expressed by a product of light emitting area and solid angle becoming larger than the Etendue value of the display device which is expressed by a product of the area of the display device and solid angle.
To solve this problem, Japanese Unexamined Patent Publication No. 2004-341105 (JP-A-2004-341105) and Japanese Unexamined Patent Publication No. 2008-52070 (JP-A-2008-52070) disclose projectors in which excitation light is shone onto a fluorescent material layer so that fluorescent light emitted from the fluorescent material layer is used as light source light.
In the invention described in Japanese Unexamined Patent Publication No. 2004-341105 (JP-A-2004-31105) and Japanese Unexamined Patent Publication No. 2008-52070 (JP-A-2008-52070), the projector includes the light source unit in which the excitation light is shone to fluorescent material layer and which uses fluorescent light emitted from the fluorescent material layer as light source light. Projectors require light source unites which can emit light of high-luminance and high-intensity, and such light can be emitted by increasing the quantity of excitation light. However, using a plurality of excitation light sources to increase the quantity of excitation light leads to an increase in heat value and an increase in consumed power. In addition, such an attempt also leads to an increase in size of a main body of a projector.